The present invention relates to a method and apparatus for monitoring the operational state and stand-by of a battery, and more particularly to such a method and apparatus that averages actual values of battery current and voltage and determines the mode of operation from the direction of the battery current.
Monitoring devices are commercially available which monitor the operational state and the stand-by of a battery, in particular those that monitor the battery of an uninterruptible power system. Such a monitoring device does not directly intervene in the installation being monitored. The following curves or family of curves can be created and deposited in a memory of a monitoring device from the known discharge curves describing a battery cell with sufficient precision:
cell voltage as a function of the relative withdrawn capacity with current or discharge time as a parameter; PA0 absolute withdrawn capacity as a function of the discharge current or the discharge time; PA0 cut-off voltage as a function of the discharge current; PA0 initial discharge voltage as a function of the discharge current; and PA0 charging voltage as a function of the withdrawn capacity.
The type of battery voltage and depends on the operational state (charging or discharging) of the battery. Determining whether charging or discharging is taking place can be made by a processor of a monitoring device in conjunction with the direction of the battery current. The battery's actual values detected in the different operational states supplied to this monitoring device are compared with the stored curves or family of curves of the battery cell.
Since the evaluation of the battery's actual values requires several curves or family of curves, the monitoring device requires large storage space and the evaluation method is complex.
The present invention is directed to the problem of developing a metal and an apparatus for monitoring the operational state and readiness of a battery having a reduced required storage space and a simplified evaluation method.